The present invention relates to a guide apparatus having a track rail and a moving block relatively movably attached to the track rail with a plurality of rolling elements (balls or rollers) interposed therebetween. More particularly, the present invention relates to a guide apparatus suitable for use in a case where a moving block is assembled to a track rail having an endless annular shape or to a track rail having a rolling element rolling surface that turns uphill at both ends thereof.
It should be noted that the term “relatively movable” as used herein means that the moving block and the track rail are movable relative to each other, such as in a case where the track rail is fixed, and the moving block is movable, and in a case where the moving block is fixed, and the track rail is movable.
There is a guide apparatus having a moving block relatively movably attached to a track rail with a multiplicity of rolling elements interposed therebetween.
In such a guide apparatus, conventionally, the moving block cannot be assembled onto the track rail from thereabove (so that the moving block is mounted astride the track rail). Therefore, the moving block is assembled onto the track rail from an end of the rail.
In a case where the track rail is formed in an endless annular shape, or in a case where the track rail has a rolling element rolling surface that turns uphill at both ends thereof, however, the moving block cannot be assembled to the track rail from an end of the rail.
Accordingly, the conventional practice is to form an intermediate portion of a predetermined length of the track rail as a separate removable part. When the moving block is to be assembled to the track rail, the removable part portion is removed from the track rail, and the moving block is assembled to the track rail from an end of an intermediate part of the track rail from which the removable part portion has been removed. Thereafter, the removable part portion is returned to the previous position and secured to the track rail.
It is also conceivable to arrange the moving block body so that it can be assembled to the track rail from thereabove, and to split each end plate into a pair of split parts in a width direction (i.e. a direction perpendicular to the direction of travel) as disclosed in Japanese Patent Application Unexamined Publication (KOKAI) No. Sho 58-142017. In assembly process, after the moving block body has been assembled to the track rail, an end plate formed from a pair of split parts is secured to each end of the moving block body in the travel direction. With this arrangement, the moving block can be assembled to the track rail even if it has an endless annular shape or it has a rolling element rolling surface that turns uphill at both ends thereof.
Japanese Patent Application Unexamined Publication (KOKAI) No. Hei 8-21440 discloses a guide apparatus including a moving block having a special structure so that the moving block can be attached to and detached from an endless annular track rail sideways.
According to the first-mentioned conventional method, each end plate is split into a pair of split parts in the width direction, and after the moving block body has been assembled to the track rail, an end plate formed from a pair of split parts is secured to each end of the moving block body in the travel direction, as disclosed in Japanese Patent Application Unexamined Publication (KOKAI) No. Sho 58-142017. This method has the problem that it is difficult or impossible to position the split parts of the end plate with respect to each other with high accuracy. Even if the end plate split parts have been positioned with respect to each other accurately, displacement is likely to occur during use.
The guide apparatus disclosed in Japanese Patent Application Unexamined Publication (KOKAI) No. Hei 8-21440 needs to use a moving block body and end plates having special structures in order to allow the moving block to be attached to and detached from the track rail sideways. Conventional standard moving block body and end plates cannot be used in the prior art apparatus.